[downloader/ism] fix AVC Decoder Configuration Record creation in python 3

youtube_dl/downloader/ism.py

@@ -149,9 +149,7 @@ def write_piff_header(stream, params):
         if fourcc in ('H264', 'AVC1'):
             sps, pps = codec_private_data.split(u32.pack(1))[1:]
             avcc_payload = u8.pack(1)  # configuration version
-            avcc_payload += sps[1]  # avc profile indication
-            avcc_payload += sps[2]  # profile compatibility
-            avcc_payload += sps[3]  # avc level indication
+            avcc_payload += sps[1:4]  # avc profile indication + profile compatibility + avc level indication
             avcc_payload += u8.pack(0xfc | (params.get('nal_unit_length_field', 4) - 1))  # complete represenation (1) + reserved (11111) + length size minus one
             avcc_payload += u8.pack(1)  # reserved (0) + number of sps (0000001)
             avcc_payload += u16.pack(len(sps))